Obstetric Haematology Flashcards
During normal pregnancy…
- Less iron required
- There is an increase in haemoglobin concentration
- The platelet count falls
- The neutrophil count falls
The platelet count falls
How does the FBC change in pregnancy?
- Mild anaemia
- –Red cell mass rises (120 -130%)
- –Plasma volume rises (150%) = net dilution
- Macrocytosis–Normal–Folate or B12 deficiency
- Neutrophilia
- Thrombocytopenia
- –increased platelet size
What are the demands of pregnancy?
- Iron requirement
- Folate requirement
Describe iron requirement.
–300mg for fetus
–500mg for maternal increased red cell mass
–RDA 30mg;
– Increase in daily iron absorption:1-2mg to 6mg
Describe folate requirement.
–Growth and cell division
–Approx additional 200mcg/day required
What is the consequence of iron deficiency?
may cause IUGR, prematurity, postpartum haemorrhage
Describe iron homeostasis.
How does the iron cycle differ in pregnancy?
What is the recommendation of iron and folate in pregnancy?
nFolic acid
–Advise reduces risk of neural tube defects
–Supplement before conception and for ≥ 12 weeks gestation
–Dose 400μg / day
Iron
–No routine supplementation in UK
What is the content of elemental iron?
Pregaday 100mg,
Pregnacare 17mg,
Ferrous Sulphate 65mg (in 200mg dose) ,
Continue for 3 months following correction of Hb
Define anaemia in pregnancy-
Definition
–Hb < 110 g/l 1st trimester
–Hb < 105 g/l 2nd and 3rd trimester
–Hb < 100 g/l postpartum
How do we diagnose iron deficiency anaemia?
How does platelet count change in pregnancy?
Falls in pregnancy
Non-pregnant: 225-249 x 109/L
Pregnant: 175-199 x 109/L
How does platelet count change in pregnancy?
Falls in pregnancy
Non-pregnant: 225-249 x 109/L
Pregnant: 175-199 x 109/L
What are the causes of thrombocytopenia in pregnancy?
- Physiological:
- –‘gestational’/incidental thrombocytopenia
- Pre-eclampsia
- Immune thrombocytopenia (ITP)
- Microangiopathic syndromes
- All other causes: bone marrow failure, leukaemia, hypersplenism, DIC etc.
If plt < 150 x 109/L, < 100 x 109/L, < 70 x 109/L - what is the most likely cause?
What is gestational thrombocytopenia? What is the mechanism? What number is sufficient for delivery? Who is affected? How does it resolve?
- Physiological decrease in platelet count ~ 10%
- >50x109/l sufficient for delivery (>70 for epidural)
- Mechanism poorly defined– Dilution + increased consumption
- Baby not affected
- Platelet count rises D2 – 5 post delivery
How many women with pre-eclampsia get thrombocytopenia? Why does it occur= What is associated with? How does it resolve?
- 50% get thrombocytopenia
- Proportionate to severity
- Probably due to increased activation and consumption
- Associated with coagulation activation–(incipient DIC – normal PT, APTT)
- Usually remits following delivery
How common is ITP in pregnancy? How is it managed? What are the effects of it?
- 5% of thrombocytopenia in pregnancy
- TP may precede pregnancy
- Early onset
- Treatment options (for bleeding or delivery)
- IV immunoglobulin–Steroids etc.
- Baby may be affected
- Unpredictable (platelets <20 in 5%)
- Check cord blood and then daily
- May fall for 5 days after delivery
- Bleeding in 25% of severely affected (IVIG if low)
- Usually normal delivery
What happens in microangiopathic syndromes? What are the consequences?
–Deposition of platelets in small blood vessels
–Thrombocytopenia
–Fragmentation and destruction of rbc within vasculature
Organ damage (kidney, CNS, placenta
What are the MAHA syndromes?
Delivery does not alter course of TTP or HUS
What are the MAHA syndromes?
Delivery does not alter course of TTP or HUS
Coagulation changes in pregnancy…
- Increase the likelihood of bleeding
- Result in a hyperfibrinolytic state
- Are mediated by betaHCG
- Result in a leading cause of maternal mortality
Result in a leading cause of maternal mortality
VTE in pregnancy
B
What are the causes of mortality in pregnancy?
- VTE - most common
Summarise the major changes in pregnancy.
What are the net changes in coagulation in pregnancy?
What are the RFs of PEs in pregnancy?
- Post-partum followed by 1st trimester
- BMI > 25
- Age > 40
What us the incidence of thrombosis in pregnancy?
- 1 per 1000 <35 years
- 2 per 1000 >35 years
- Relative risk approx. x10
- One third are post partum (only 6 weeks)
- Doppler and VQ are safe to perform in pregnancy
- D-dimer often elevated in pregnancy–Not useful for exclusion of thrombosis
What improvements have been made in order to prevent maternal deaths?
Improved assessment of risk
Public health education: identify women at risk because of their weight, family history or past history to seek advice before becoming pregnant. RCOG guidelines 2004
Increased recognition of symptoms in early pregnancy - chest pain / SOB / leg pain
Diagnosis - Increased awareness that diagnostic tests (VQ / CXR / Venogram/ CTPA) are safe
Treatment
- Wider use of thromboprophylaxis
- Therapy should be given pending the results of further testing
What is the prevention of thromboembolic disease in pregnancy?
- Women with risk factors should receive prophylactic heparin +TED stockings
- –Either throughout pregnancy
- –Or in peri-post- partum period
- –Highest risk get adjusted dose LMWH heparin
- Mobilise early
- Maintain hydration
How do we treat thromboembolic disease in pregnancy?
- Management
- LMWH as for non-pregnant
- Does not cross placenta
- RCOG recommend once or twice daily
- Do not convert to warfarin (crosses placenta)
- After 1st trimester monitor anti Xa
- 4 hour post 0.5-1.0u/ml
- LMWH as for non-pregnant
- Stop for labour or planned delivery, esp. for epidural
- Epidural: wait 24 hours after treatment dose, 12 hours after prophylactic dose
What is chrondrodysplasia punctata?
What is the consequence of anti phospholipid syndrome?
Why does fatal bleeding occur? What do we do?
How do we determine PPH? How common is >1L loss? How company require transfusions?
- Post Partum Haemorrhage (PPH) : > 500 mL blood loss
- 5% of pregnancies have blood loss >1 litre at delivery.
- Requiring transfusion post partum
- –1% after vaginal delivery
- –1-7% after C-Section
What is the mechanism of PPH?
- major factors are
- uterine atony
- trauma
- haematological factors minor except
- dilutional coagulopathy after resuscitation
- DIC in abruption, amniotic fluid embolism etc.
What is DIC precipitated by in pregnancy?
- Coagulation changes in pregnancy predispose to DIC.
- Decompensation precipitated by:
- Amniotic fluid embolism
- Abruptio placentae
- Retained dead fetus
- Preeclampsia (severe)
- Sepsis
What is amniotic fluid embolism? How common is it? How does it present? What is the mortality associated with it? When does it occur?
What are the aims of haemoglobinopathy screening?
How do we detect haemoglobinopathies?
How do we counsel about haemoglobinopathies?
How do we differentiate between iron deficiency anaemia and thalassaemia trait?
D
B
B
HELLP syndrome
Iron deficiency
